Native-Level Popup Notification Integration

I am currently developing an app using Capacitor, and I need a skilled developer to integrate a native-level popup notification into the app. This notification should appear on the screen when a call or video call is received, even if the app is in the background or has been terminated.

Key Features of the Notification:
- Displaying the caller's name and profile image
- Indicating the call type (voice/video)
- Providing Accept and Reject buttons

A successful integration would ensure that:
- Clicking 'Accept' opens the app and navigates to the call screen
- Clicking 'Reject' dismisses the popup and optionally sends a reject response to the backend

The app is currently in development and the backend functionality to handle the call notifications is only partially implemented. Therefore, I am looking for a freelancer with:
- Strong experience with Capacitor and app development
- Proficiency in integrating native-level features into apps
- Capability to assist in enhancing the backend functionality if necessary.